1. Field of the Invention
The present invention relates to an ion exchange chromatography process for purifying a peptide from a mixture containing said peptide and related impurities and to an industrial including such ion exchange chromatography process.
2. Description of the Related Art
For the purification and analysis of proteins and peptides, chromatography is a well-known and widely used method. A number of different chromatographic principles are applied, among these ion exchange chromatography (IEC). The IEC principle includes two different approaches: anion exchange and cation exchange according to the charge of the ligands on the ion exchange resin. A conventional IEC purification process usually consists of one or more: equilibration sections, application or loading sections, wash sections, elution sections, and regeneration sections (cf. Remington's Pharmaceutical Sciences, Gennaro, ed., Mack Publishing Co., Easton, Pa., 1990, or Remington: The Science and Practice of Pharmacy, 19th Edition (1995)).
The main principle of elution in IEC in industrial purification processes is salt component gradients in an aqueous buffer solution at constant pH, either as step or linear gradients (cf. S. Bjørn and L. Thim, Activation of Coagulation Factor VII to VIIa, Res. Discl. No. 269, 564–565, 1986). Isocratic elution is possible, but seldom used. Organic solvents or modifiers have occasionally been added to the solutions to keep the protein or peptide on the desired form or just in solution (cf. K. H. Jørgensen, Process for Purifying Insulin, U.S. Pat. No. 3,907,676, Sep. 23, 1975; and J. Brange, O. Hallund and E. Sørensen, Chemical Stability of Insulin 5. Isolation, Characterisation and Identification of Insulin Transformation Products, Acta Pharm. Nord. 4(4), 223–232, 1992). Also, the change in pH may occasionally be employed to elute the target protein (cf. J. Lamy, J. Lamy, J. Weill, Arch. Biochem. Biophys. 193, 140–149, 1979).